HVAC Installation: What kind of heating and cooling system do I have?

In Tennessee, there are four primary types of HVAC systems that are commonly found in residential applications. Most homes will either have a split system heat pump, a packaged heat pump, a split gas/electric system or a gas/electric packaged system. The difference is, two of those units solely rely on electricity for heating and the other two rely on gas and electricity. In some rare cases, you will find homes in Tennessee with a single stage electric heating system which is basically electric heating without the added benefit of a heat pump. We will explain the difference between the two in a minute. For now, let’s start out learning the difference between a packaged system and a split system.

Understanding the Difference

Split Systems

http://www.andrewsair.net/images/TWE_VS_Cut.jpghigh efficiency unit  A split system is basically two separate pieces of equipment that are working together to produce your heating and air conditioning. One half of the system is located outside the home and the other half is on the inside usually found in a basement, attic, closet or garage. Most split systems have vents connected to the ceiling or wall but they can also be in the floor if the inside unit is located in a basement, closet or garage.

Packaged System 

Gas Indoor and Outdoor Units A packaged system is basically as it sounds, meaning that the entire system is packaged together into one piece of equipment and is  always located outside the home. Packaged systems are larger units that are typically square or rectangular in shape. The return and supply air trunk lines attach to the outdoor unit and from there the ductwork runs  through an opening in the side of your home and into a crawlspace where it then distributes air through your vents which are normally located in the floor

Do I Have Gas Or Electric Heat?

Now that you have learned the difference between a split and a packaged system, we can go on to the next step which is to determine if you have a gas or electric heating system. If your home relies on a gas furnace for heating, then you will have a gas meter or propane tank located somewhere on your property and there will be some sort of gas pipe connecting to your inside or outside system. Another easy way to tell is by removing your thermostat from the wall. If there are only 4-5 wires hooked up to the thermostat and you can confirm that you have gas on the property, chances are you have a gas/electric split or packaged system.

Single Stage Electric Heat vs Heat Pump

For those of you that don’t have a gas heating system, it is important to make sure that you do in fact have a heat pump and not a single stage electric heating system. Most contractors know not to install a single stage electric type system here in Tennessee because they are highly inefficient considering that our winter season averages between 30-40 degrees. Heat pumps are 2-4 times more efficient than single stage electric system which is why there are so many of them being utilized in our state. During the winter season, a heat pump generates and transfers 2-4 times more heat than a straight electric heater which of course decreases the amount of energy it takes to heat your home. Single stage electric heat is nothing more than a large toaster that’s glowing bright orange with a fan blowing air across its hot coils which in turn sends its generated heat through your ductwork, out your vents and into your home. If you have a heat pump, there should be a “heat” and “emergency heat” setting somewhere on your thermostat either on a digital touch screen display or next to a switch. To confirm that you have a heat pump, simply set the thermostat to heat (not emergency heat) and set the temperature to 4 degrees above the actual room temperature. Go outside to your HVAC unit and see if the outdoor fan or compressor turns on within a 5 minute period. If it does, then chances are you have a heat pump. With a heat pump, it is normal for the outdoor condenser fan and compressor to operate frequently during the winter season. If you have a single stage electric heating system, the condenser fan and compressor will only operate when the thermostat is set for cooling.

Electric Heat Pumps- Split and Packaged Units

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In the Middle Tennessee area, there are no shortages of houses with heat pump units, and there’s a very good reason why. Although gas furnaces can heat an environment much faster than electric, heat pumps can still be relatively efficient as long as they are utilized in mild winter climates. Because Tennessee doesn’t normally have a lot of heavy winters, an electric heat pump is considered by many to be a suitable alternative to natural gas or propane because it can provide just enough heat to keep you satisfied throughout the winter season without it costing you an arm and a leg.

The key to saving money with a heat pump is a combination of…

  • A system with a 14 SEER rating or better (Similar to buying a car that gets better gas mileage)
  • A programmable or wifi thermostat (saves wear and tear on you unit, save money on utilities)
  • Good insulation around the perimeter and ceiling of the home (Walls an attics account for about 70% of a home’s heat loss)
  • High efficiency windows (Windows account for about 10% of a home’s heat loss)
  • Well insulated ductwork (Poorly insulated ductwork in unconditioned spaces like an attic or crawlspace can cause you to lose 50-60% of its generated heat by the time it gets to you vents)
  • Routine maintenance (Restricted airflow and improper refrigeration pressures are the most common reasons why a system runs inefficiently or fails prematurely)
  • Frequent filter changes
  • A good duct design and proper equipment sizing (Poorly designed duct work will not only increase wear and tear on your equipment, it will also cause balancing issues which means some rooms will likely be a lot cooler or warmer than others. A bad duct design can also create other  issues such as high humidity which can create mold problems within your HVAC system)

Keep in mind, heat pumps do tend to have more mechanical problems than gas units only because they have more components and most of those parts have to operate year round. The compressors, capacitors, contactors, condenser fan motors and other refrigeration components are more likely to wear out faster on a heat pump than a gas system mainly because they have to operate during all four seasons of the year as opposed to a gas system that only uses its components during the spring and summer. Because heat pumps operate year round, it is extremely important to have someone clean and service your unit twice a year so that they can best endure the heavy work load. Often time’s, a heat pump can send a variety of false signals, especially during the fall and winter season. Because there are two stages of heat, it’s often times easy to get the sense that everything’s working fine because the house is staying at whatever temperature you have set it at. If however the unit is low on refrigerant or the 2nd stage heat isn’t working, the unit can still keep the house warm on slightly cold days but you will have efficiency and shortage of heat problems if the temperature drops into freezing. When a unit is only operating with one stage of heat, it will run longer, use a lot more electricity and put a heavier work load on the unit. This is another reason why spring and fall cleanings are so important to budget for.

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